Tip-toe posterior pelvic tilt

Stand on your toes with your arms extended upwards, mimicking the final position you would have in a handstand.

Contract your abs, hamstrings, and glutes simultaneously to rotate your hips backwards, eliminating the lumbar curvature.

When you return to the starting position, exaggerate the opposite movement, maximizing your lumbar curvature so you can feel the difference between the two positions.